多層式白光有機電激發光元件之研究

Abstract

利用DSA-ph和tb-Rubrene，我們可以得到一個最高效率將近10.5 cd/A的白光元件。經由改變藍光和黃光的客發光體，我們可以得知藍光的效率會決定整個白光的效率，而黃光是用來調整整個EL的圖譜。 為了抑制元件CIE值會隨著電流密度改變的問題，我們加入了電洞阻擋層(Balq)和電子阻擋層(NPB)，結果成功的讓CIE值的改變小於0.02。不過也因為加入了NPB和Balq的關係，導致元件產生過多的焦爾熱，會使元件產生局部的結晶問題，不利於元件的穩定度。 兩波段白光的EL圖譜因為缺少530 nm和600 nm這兩部分，所以經過彩色濾光片後，得到的NTSC比例只有58.7 %。為了提升NTSC的比例，我們在Alq3中摻雜入C545T這個綠光材料和之前由實驗室學長所發展出來的紅光系統，用來補足530 nm和600 nm的部分。這個三波段白光在20 mA/cm2時的效率為8.16 cd/A，CIE為(0.31,0.41)，功率效率為2.86 lm/W，外部量子效率為3.85 %。經過彩色濾光片後，得到的NTSC比例為66.5 %，相較於兩波段白光的58.7 %，大大的提升了7.8 %。

The efficiency of 10.5 cd/A can be achieved for our white OLED using DSA-ph and tb-Rubrene as emitting dopants. By changing different dopant materials, the efficiency of white OLED was known to be determined by the blue emitting materials. In order to suppress the problem of CIE fluctuation due to different current density, NPB and Balq were inserted as carrier blockers. As the result, the variation of CIE can be reduced to less than 0.02. Unfortunately, the device degradation occurred by joule heating after prolong operation. When the above-mentioned white light was passed through color filter arrays, its ratio relative to the NTSC was only 58.7 %. In order to increase the ratio, C-545T and co-host system were introduced into our three element white devices and the ratio could be raised by 7.8 % to reach 66.5 %.